dè chừng 
guard against-foresee the eventuality of [ dè ] : (1) moderate, reserved; (2) to take care, spare, (3) to expect, foresee
[ chừng ] : about, approximately; rough measure, rough extent, rough estimate
Most Common Compounds Set 1:
Most Common Compounds Set 2 :
bắt bóng dè chừng at random, at a guess, by guesswork